This image shows the infrared emission from the young star Fomalhaut and the dust disk surrounding it, as recorded with ESA's Herschel Space Observatory at a wavelength of 70 micron. To explain the emission from Fomalhaut's debris disk, astronomers invoke a steady production of dust particles via comet collisions, with an average rate of 2,000 daily collisions between comets of 0.6 mile (1 kilometer) across or, alternatively, of two daily collisions between 6-mile-diameter (10km) comets.